With increasing density of electronic devices, the number of contacts of circuit board connectors loaded on a circuit board is increasing and becoming more dense. Generally, such a circuit board connector comprises a first connector which has resilient metal contacts and a second connector which has nonresilient metal contacts.
Among these, the second connector is conventionally manufactured by combining a rigid housing made of insulating resin and many nonresilient metal contacts. The manufacturing method of the second connector may be (1) an insertion method in which contacts formed by stamping and/or forming are fixed in a housing by pressing or snapping the contacts in or on the housing; or (2) an injection molding method in which the contacts formed in the same manner as described in the foregoing are positioned in the mold into which insulating resin is injected to fix the contacts in the housing.
Furthermore, another connector manufacturing method is directed to a method of injection mold circuit device of which the surface is partly covered with a metal by plating, etc. (Molded Interconnection Device, hereafter called MID). The two-shot mold method is the method in which a double molding is performed with the resin, which can accept plating, and the resin, which cannot accept plating, and the metal coating is formed only on the resin which can accept plating.
The connector manufactured by using such a two-shot mold method is disclosed in Japanese Patent Publication No. 2-78171. FIGS. 15 and 16 show the manufacturing process of such a connector. First, a resin, which cannot accept plating, is molded to form an insulating base 100 of which the cross section is approximately of an inverted T-shape. Then, a resin, which can accept plating, is molded in the narrow grooves 102 of the insulating base 100 to form contact regions 104 (FIG. 16), and by plating, using a runner 106 as the plating electrode, metal coatings are formed only on the surface of the contact regions 104. Subsequently, by cutting the gates 108, the connector, of which the conductor patterns are formed in the designed pitch, is completed.
However, with the increasingly narrower pitch and high number of terminals, the following problems arise in the conventional connector which is made by the combination of the insulating resin housing and the metal contacts. That is, the increasingly narrower pitch causes difficulty in the formation of the contacts and the housing, as well as the difficulty in assembly of the contacts to the housing. Furthermore, because of such difficulties, the manufacturing cost rises. Also, the increasing number of terminals causes nonuniformity in the soldered surface of the contacts to the circuit board, and it becomes difficult to maintain the coplanarity of the soldered surface. Furthermore, it is necessary to improve the precision in position in order to attain the designed pitch between the contacts.
Now, in the case of the connector to which the two-shot mold method of MID is applied, it is practically impossible to form conductor patterns in narrow pitch, for example, 0.5 mm pitch, etc., since the conductor patterns are formed by double molding. This is because, with an increasingly narrower pitch, the volume of the contact region is drastically decreased, and the flow of the resin, which accepts plating, is impeded. Also, since the gates 108 are in a single row, the conductor patterns are also in a single row, which is inappropriate for the connector of high density. Furthermore, since the molds are required for the two resins, this results in a higher manufacturing cost.
Consequently, the objective of the present invention is to provide a connector which solves the aforesaid problems.